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Medycyna Środowiskowa - Environmental Medicine 2015, Vol. 18, No. 2, 32-38
www.environmental-medicine-journal.eu
www.medycynasrodowiskowa.pl
Sanitary condition of electrical hand dryers in toilets of shopping centres in Kraków
Stan sanitarno-higieniczny elektrycznych suszarek do rąk w toaletach centrów handlowych
na terenie miasta Krakowa
Anna Lenart-Boroń (a, b, c, d, e), Jordan Jarosiński (b, c, d)
Department of Microbiology, Faculty of Agriculture and Economics, University of Agriculture in Kraków, Poland.
Head of the Department of Microbiology: Prof. PhD Eng. M.J. Chmiel; Rector of the University of Agriculture: Prof. W. Sady
concept and design
planning of experimental methods
(c)
conducting research
(d)
analysis of results and conclusions
(e)
writing the manuscript
(a)
(b)
AbstrAct
Introduction. Shopping habits have changed over the
past several years and consumers choose shopping centres,
where they can spend time and visit restaurants. People
usually wash hands before meals, but toilets in shopping
centres are visited by hundreds of users every day which
makes their cleanliness questionable. Therefore, the aim
of this study was to assess the sanitary condition of electrical hand dryers in toilets of the selected shopping centres in Kraków.
Material and methods. Air was sampled at the outlet
of electrical hand dryers and surface swabs of hand dryers
were taken in toilets of five shopping centres. Air sampling
was conducted using the MAS-100 impactor. The number
of mesophilic bacteria, fungi, actinomycetes, staphylococci and Escherichia coli was determined. The results of
air analyses were compared with the limits provided by
the Polish Standards on air quality.
Results. The number of microorganisms varied between the studied centres. In terms of mesophilic bacteria
and fungi the air was unpolluted. The concentration of
actinomycetes however significantly exceeded the limits
set by the Polish Standards. Numerous Escherichia coli
were found both in the air and in swabs in one of the
centres. However the number of E. coli and staphylococci
did not exceed the minimum infective dose.
Conclusions. The studies showed high concentrations of airborne actinomycetes and staphylococci. Also
the presence of E. coli in the air and swabs allows the
conclusion that legal regulations for concentrations of
airborne microorganisms are necessary to make people
aware of this problem. However, it was found that using
electrical hand dryers does not have impact on human
health.
Nadesłano: 18.11.2014
Zatwierdzono do druku: 15.05.2015
Keywords: air, airborne microorganisms, Escherichia
coli, staphylococci
strEszczENiE
Wstęp. W przeciągu ostatnich lat zwyczaje konsumentów znacznie się zmieniły i klienci coraz częściej rezygnują
z osiedlowych sklepów na rzecz centrów handlowych,
w których mogą spędzić czas, a także skorzystać z bogatych
ofert restauracji. Wielu ludzi odruchowo myje ręce
przed posiłkami, jednak toalety w centrach handlowych
odwiedzane są przez setki osób dziennie, a ich czystość
może być wątpliwa. Celem badań była ocena stanu sanitarno-higienicznego suszarek do rąk w toaletach wybranych
centrów handlowych w Krakowie.
Materiały i metody. Pobrano powietrze u wylotu suszarek elektrycznych oraz wymazy powierzchniowe wylotów powietrza w suszarkach w toaletach pięciu centrów
handlowych. Próbki powietrza pobrano przy użyciu impaktora MAS-100. Oznaczono liczebność bakterii mezofilnych, grzybów, promieniowców, gronkowców i Escherichia coli. W przypadku badań powietrza wyniki porównano z zaleceniami Polskich Norm dotyczących jakości powietrza atmosferycznego.
Wyniki. Liczebność drobnoustrojów w badanych centrach handlowych była zróżnicowana. Pod względem liczby
bakterii mezofilnych i grzybów powietrze we wszystkich
toaletach było niezanieczyszczone. Stężenie promieniowców
znacznie przekraczało wartości dopuszczalne w Polskich
Normach. Również liczba gronkowców była bardzo wysoka. W jednym z badanych centrów stwierdzono liczne bakterie Escherichia coli, zarówno w powietrzu, jak i w wymazach. Jednak liczebność zarówno E. coli jak i gronkowców
nie przekroczyła granicy minimalnej dawki infekcyjnej.
Niniejszy materiał jest udostępniony na licencji Creative Commons – Uznanie autorstwa 3.0 PL. Pełne
postanowienia tej licencji są dostępne pod: http://creativecommons.org/licenses/by/3.0/pl/legalcode
Medycyna Środowiskowa - Environmental Medicine 2015, Vol. 18, No. 2
Anna Lenart-Boroń, Jordan Jarosiński: Sanitary condition of electrical hand dryers in toilets of shopping centres in Kraków
33
Wnioski. W badaniach stwierdzono wysokie stężenia
promieniowców i gronkowców. Obecność E. coli w powietrzu i w suszarkach daje podstawę do stwierdzenia,
że normy prawne regulujące stężenie mikroorganizmów
w powietrzu są potrzebne, aby podkreślić znaczenie pro-
blemu. Stwierdzono jednakże, że korzystanie z elektrycznych suszarek do rąk nie zagraża zdrowiu użytkowników.
iNtroductioN
The sampled air volume was 100 litres. Both air
and swab samples were collected on Petri dishes
containing microbiological media used for enumeration of mesophilic bacteria (Trypticasein Soy Lab
Agar, BTL, Poland), fungi (Malt Extract Agar, Oxoid,
Great Britain), actinomycetes (Actinomycete Isolation Lab Agar, Biocorp, Poland), mannitol-positive
and mannitol-negative Staphylococcus spp. (Mannitol Salt Agar, BTL, Poland), Escherichia coli (EndoLes Agar, BTL, Poland). All samples were collected
in three replications and data were presented as
mean values of those. The air temperature and humidity was recorded using and HT-9213 Thermohydrometer (ATM, China). After sampling Petri
dishes were incubated at 37°C for 48 hrs (mesophilic
bacteria, Staphylococcus spp., Escherichia coli) or at
25°C for 3–5 days (fungi) and for 5–7 days (actinomycetes). After incubation, the number of colonies
characteristic for each of the examined microbial
group was counted and expressed as the number of
colony forming units per cubic meter of air
(CFU/m3) in the case of air sampling and the number of colony forming units in the case of surface
swabs. For Staphylococcus spp. and Escherichia coli
enumeration on agar plates was followed by microscopic observations of Gram-stained smears. The
numbers of airborne microorganisms were compared with the limits for atmospheric air contamination, given in the Polish Standards [4, 5]. The actual colony count was corrected according to the
positive hole correction table [6].
Statistica v. 10.0 software (StatSoft, US) was used
to calculate basic descriptive statistics and one-way
analysis of variance was applied to determine the
significance of differences in the number of microorganisms between different shopping malls.
Over the past several years shopping habits in
Poland have changed. Small local shops are being
replaced by a growing number of shopping malls,
in which spending free time is becoming increasingly popular. Apart from a wide variety of clothing,
electronic or grocery shops, people can spend time
in restaurants. Although it is not obvious for everyone, most people have the habit of washing hands
before meals. Thus, the sanitary condition of toilets,
used by hundreds of people every day, is an important issue, as inadequate care of the cleanliness of
such places may turn out counterproductive.
Microorganisms do not reproduce in air, because
the environment is too dry for them but air is a very
good transmitter of microorganisms [1]. Also,
Gram-positive bacteria and spore-forming microorganisms (including fungi) are quite resistant to drying, therefore they can dwell in such environment
for a long time [1]. It has been found that the transmission of bacteria is more likely to occur from
wet than on dry skin. Therefore, proper drying of
hands should be an essential part of hand hygiene,
especially before meals [2]. There have been concerns, whether using electrical hand dryers is as efficient and hygienic as disposable paper towels [2].
Redway and Fewdar [3] found numerous bacteria
in jet air dryer surfaces, including Pseudomonas
aeruginosa, Escherichia coli and various Bacillus
species, concluding that the hand dryers can contribute to the transmission of potentially pathogenic bacteria.
The presented study was aimed at assessing the
sanitary condition of electrical hand dryers located
in toilets close to eating places in the selected shopping malls in Kraków.
MAtEriAl ANd MEthods
The study was conducted based on air sampling
by the outlet of air from the electrical hand dryers
and on surface swabs of the dryers’ interiors. The
samples were collected in five shopping malls, in
five toilets per shopping centre. The air was sampled
using a MAS-100 impactor (Merck, Switzerland).
Słowa kluczowe: Escherichia coli, gronkowce, mikroorganizmy w powietrzu, powietrze
rEsults
Temperature and relative humidity were measured onsite, during each sampling. However, the
conditions prevailing in shopping centres, including
their toilets, are constant. Therefore, the temperature during all measurements ranged from 20 to
22°C and relative humidity ranged from 36% to
40%.
34
The recorded numbers of all microorganisms are
presented in tab. I–V for air sampling and in fig. 15 for surface swabs. The mean number of airborne
mesophilic bacteria varied between the examined
shopping centres, from 140 CFU/m3 in the Centre
2 to over 700 CFU/m3 in the Centre 5 (tab. I). The
greatest number of airborne mesophilic bacteria
(1190 CFU/m3) was recorded in one of the toilets
in the Centre 4.
Tab l e I. Numbers of airborne mesophilic bacteria detected in
the toilets of the examined shopping centres [CFU/m3]
Tabela I. Liczebność bakterii mezofilnych w powietrzu toalet
badanych centrów handlowych [jtk/m3]
Min
Max
Mean
Median
Standard
deviation
Centre 1 Centre 2 Centre 3 Centre 4 Centre 5
30
300
156
120
50
280
140
70
410
870
652
630
131.64
114.89
174.70
250
1190
564
470
350
990
732
770
366.58
274.63
Mean numbers of airborne fungi ranged from 14
CFU/m3 in the Centre 3 to 130 CFU/m3 in the Centre 5 (tab. II). Also Centre 5 was the one in which
the greatest number of airborne fungi was recorded
during this study and it was 220 CFU/m3.
Tab l e II. Numbers of airborne fungi detected in the toilets of
the examined shopping centres [CFU/m3]
Tabela II. Liczebność grzybów w powietrzu toalet badanych
centrów handlowych [jtk/m3]
Min
Max
Mean
Median
Standard
deviation
50
150
86
70
40.37
10
70
30
30
0
50
14
10
24.49
20.74
0
100
32
20
30
220
130
140
39.62
70.71
The number of airborne actinomycetes in toilets
of the examined shopping centres was generally
low, with the exception of the Centre 1, where both
the greatest mean number and the maximum number of these microorganisms was recorded (mean –
454 CFU/m3, max – 1140 CFU/m3, tab. III). No airborne actinomycetes were recorded in the Centre 5,
where all values equaled 0 CFU/m3.
Tab l e III. Numbers of airborne actinomycetes detected in the
toilets of the examined shopping centres [CFU/m3]
Tabela III.Liczebność promieniowców w powietrzu toalet badanych centrów handlowych [jtk/m3]
Min
Max
Mean
Median
Standard
deviation
30
1140
454
350
0
10
2
0
435.24
0
10
4
0
4.47
5.48
0
10
2
0
0
10
0
0
4.47
0
Mean number of mannitol-positive staphylococci
ranged from 4 CFU/m3 in the Centre 1 to 248
CFU/m3 in the Centre 5. The maximum number of
these microorganisms (i.e. 410 CFU/m3) was recorded in both Centre 5 and Centre 4 (tab. IV). On the
other hand, the mean number of mannitol-negative
staphylococci ranged from 8 CFU/m3 in the Centre
1 to 284 CFU/m3 in the Centre 5. The maximum
number of these bacteria was also recorded in the
Centre 5 and it was 400 CFU/m3 (tab. III).
Except for the Centre 1, airborne E. coli was not
detected or was detected in very low numbers (tab.
V). Mean numbers of these bacteria ranged from 2
CFU/m3 in the Centre 3 to as much as 186 CFU/m3
in the Centre 1. This was also the place where the
greatest number of E. coli was recorded, i.e. 340
CFU/m3.
Tab l e IV. Numbers of airborne mannitol-positive and mannitol-negative staphylococci detected in the toilets of the examined
shopping centres [CFU/m3]
Tabela IV. Liczebność gronkowców mannitolododatnich i mannitoloujemnych w powietrzu toalet badanych centrów handlowych
[jtk/m3]
Centre 1
Min
Max
Mean
Median
Standard deviation
M+
0
20
4
0
8.94
M–
0
20
8
10
8.37
Centre 2
M+
0
60
28
10
29.50
M–
40
130
76
50
45.06
Centre 3
M+
30
240
140
150
93.54
M–
20
370
248
340
156.11
Centre 4
M+
120
410
220
200
117.26
M–
90
240
142
130
59.75
Centre 5
M+
180
410
248
230
104.74
M–
220
400
284
270
70.21
35
70
340
186
150
0
10
4
0
127.40
5.48
0
10
2
0
0
20
4
0
4.47
0
20
6
0
8.94
8.94
Mean numbers of mesophilic bacteria detected
in swabs from the surface of air outlets from examined hand dryers ranged from 12 CFU in the Centre
1 to 930 CFU in the Centre 5 (fig. 1).
Similarly, the smallest number of fungi detected
in swabs was observed for hand dryers in the Centre
930
Mean number of mesophilic
bacteria [CFU]
1000
736
800
600
414
400
200
0
232
Centre 1
Centre 2
Centre 3
Centre 4
Centre 5
Fig. 1. Mean number of mesophilic bacteria detected in swabs
from the hand dryers of each shopping centre [CFU]
Ryc. 1. Średnia liczba bakterii mezofilnych stwierdzonych w wymazach z powierzchni suszarek w poszczególnych centrach handlowych [jtk]
Mean number of fungi (CFU]
70
70
60
44
50
40
30
34
34
30
20
18
15
10
5
0
2
2
2
Centre 3
Centre 4
Centre 5
0
Centre 2
Fig. 3. Mean number of actinomycetes detected in swabs from
the hand dryers of each shopping centre [CFU]
Ryc. 3. Średnia liczba promieniowców stwierdzonych w wymazach z powierzchni suszarek w poszczególnych centrach handlowych [jtk]
250
204
180 184 184
200
150
90
100
50
48
2 2
24
0
Centre 1
10
0
20
Centre 1
12
Mean number of staphylococci
[CFU]
Min
Max
Mean
Median
Standard
deviation
1 (i.e. 30 CFU), while the greatest number was
recorded in the Centre 5 (i.e. 70 CFU, fig. 2).
On the other hand, Centre 1 was the one, where
the greatest number of actinomycetes was recorded
in the surface swabs from the air outlet of hand
dryers (i.e. 18 CFU) and in the remaining shopping
centres, values were very low and did not exceed 2
CFU. These results are consistent with the ones obtained for the air sampling (tab. III, fig. 3).
The mean number of mannitol-positive staphylococci in swabs from hand dryers ranged from 2
CFU in the Centre 1 to 244 CFU in the Centre 3,
while the mean number of mannitol-negative
staphylococci ranged from 2 CFU in the Centre 1
to 184 CFU in the Centre 5 (fig. 4).
Mean number of actinomycetes
[CFU]
Tab l e V. Numbers of airborne E. coli detected in the toilets of
the examined shopping centres [CFU/m3]
Tabela V. Liczebność E. coli w powietrzu toalet badanych centrów handlowych [jtk/m3]
Centre 2
Centre 3
Centre 4
Centre 5
Mannitol – positive staphylococci
Centre 1
Centre 2
Centre 3
Centre 4
Centre 5
Fig. 2. Mean number of fungi detected in swabs from the hand
dryers of each shopping centre [CFU]
Ryc. 2. Średnia liczba grzybów stwierdzonych w wymazach z
powierzchni suszarek w poszczególnych centrach
handlowych [jtk]
Mannitol – negative staphylococci
Fig. 4. Mean number of staphylococci detected in swabs from
the hand dryers of each shopping centre [CFU]
Ryc. 4. Średnia liczba gronkowców stwierdzonych w wymazach z powierzchni suszarek w poszczególnych centrach handlowych [jtk]
36
Mean number of E. coli [CFU]
Similarly to the results of air sampling, the greatest number of E. coli recorded in swabs from hand
dryers, was recorded in the Centre 1, while in the
remaining centres, these bacteria were either absent,
or recorded in very low amounts (fig. 5).
35
34
30
25
20
15
10
5
0
Centre 1
2
2
0
2
Centre 2
Centre 3
Centre 4
Centre 5
Fig. 5. Mean number of E. coli detected in swabs from the
hand dryers of each shopping centre [CFU]
Ryc. 5. Średnia liczba E. coli stwierdzonych w wymazach z powierzchni suszarek w poszczególnych centrach handlowych [jtk]
The statistical analysis of the results showed that
with one exception for the number of fungi in
swabs, the differences in the numbers of microorganisms between the examined shopping centres
were statistically significant (tab. VI).
Tab l e VI. Results of the analysis of variance concerning the
differences in microbial abundance in air and swabs
Tabela VI. Wyniki analizy wariancji dla różnic w liczebności badanych drobnoustrojów w powietrzu i wymazach
Microorganisms
Mesophilic bacteria
Fungi
Actinomycetes
Mannitol-positive staphylococci
Mannitol-negative staphylococci
E. coli
* – values are significant at p < 0.05
* – wartości istotne przy p < 0,05
discussioN
F value (air
sampling)
7.29*
6.34*
5.39*
8.79*
9.52*
10.08*
F value
(swabs)
3.95*
0.87
6.00*
5.44*
4.96*
3.68*
The issues related to the personal hygiene, as
well as sanitation have been of major concern, even
since the ancient times, when the human waste
management problems were among the most im-
portant ones [7]. Microorganisms, occurring in the
air of sanitary premises originate from different
sources with people and their sweat or saliva
droplets being the most significant [8]. Due to their
composition, indoor bioaerosols may cause numerous disease symptoms. It is necessary to remove
airborne microorganisms and air ventilation or air
conditioning systems are thought to be the best
way of accomplishing it; however their efficiency
or even cleanliness are not sufficient. As a result,
using air conditioning may be responsible for microbial-related health disorders [9].
The number of microorganisms recorded in this
study varied between the examined sites, both in
the case of air and swab samples. The numbers of
airborne bacteria, fungi and actinomycetes were
compared with the limit levels provided by the Polish Standards [4, 5]. The concentration of bacterial
aerosol exceeded the limit given for unpolluted air
(i.e. 1000 CFU/m3) only once – in the Centre 4. In
the remaining cases the air was considered unpolluted. Also, given the fact that the maximum number of airborne fungal cells recorded throughout
the study was 220 CFU/m3 (Centre 5), the air could
also be considered as unpolluted.
On the other hand, the concentration of airborne actinomycetes was very high in the Centre
1, where the presence of these microorganisms was
recorded in each sample and threshold values for
heavily polluted air were exceeded in almost all
samples. The minimum value recorded in this centre was 30 CFU/m3 which classifies the air as averagely polluted. In the remaining sites actinomycetes
were either not detected, or they were detected in
numbers not exceeding 10 CFU/m3. The admissible
limits of airborne actinomycete concentration are
very low and the threshold for unpolluted air is
set at 10 CFU/m3, while the concentration of more
than 100 CFU/m3 classifies the air as heavily polluted [4]. One of the reasons for such low limits is
the fact that even very low concentrations of these
microorganisms can cause allergic reactions [10].
Considering the number of mannitol-positive
and mannitol-negative staphylococci, the air in the
Centre 1 was classified either as unpolluted or the
pollution was average (tab. IV). However, the numbers of these bacteria were much higher in the remaining shopping centres, as the air pollution was
average or heavy in the Centre 2 and in the Centres
3, 4 and 5 the pollution was heavy. Similarly the
numbers of both mannitol-positive and mannitolnegative staphylococci recorded in surface swabs
from the hand dryers in the Centres 3, 4 and 5
were the highest and ranged from 40 CFU to 490
CFU. Those numbers were similar to the ones
recorded in surface swabs from jet air dryers by
Redway and Fawdar [3], as they isolated 127 CFU
of different staphylococcal species from inner surfaces of the dryers, some of which turned out to be
S. aureus. However, the concentrations recorded in
our study still do not pose a direct threat to human
health, as the infective dose of e.g. Staphylococcus
aureus reaches 103–108 cells [11].
Although the number of airborne E. coli is not
regulated, these bacteria fall within the risk group
2 of organisms that can cause illness in people
[12]. In four out of the five examined shopping
centres E. coli were hardly detected. However, in
the Centre 1 they occurred in quite high numbers,
i.e. ranging from 70 to even 340 CFU/m3 of air
and from 10 to 100 CFU in swabs, with the mean
number of 34 CFU. Similarly high number of airborne Enterobacteriaceae was observed by Budzińska et al. [13] within the municipal sewage treatment plant. Also Redway and Fawdar [3] detected
the presence of different Enterobacteriaceae species
(i.e. mean number of 85 CFU with the range of 0–
1429 CFU) in surface swabs from jet air hand dryers, including Escherichia coli (26 isolates in total).
Our observations are not too surprising, as toilet
flushing is one of the reasons for airborne transmissions of fecal bacteria, including Escherichia
coli [14]. Even though the infective dose of Escherichia coli is relatively large (more than 105 CFU)
[15], the enterohemorrhagic strains of E. coli (e.g.
O157:H7) require an infective dose of only about
10 CFU [16].
coNclusioNs
The presented study showed that in terms of
mesophilic bacteria and fungi the air in toilets of
all shopping centres was not contaminated. In the
case of actinomycetes the air was heavily polluted
only in the Centre No. 1. On the other hand, very
high concentrations of both mannitol-positive and
mannitol-negative staphylococci were recorded, indicating heavy pollution in almost all shopping
centres. Another significant observation was that
the presence of Escherichia coli was detected both
in the air and in the swabs from the hand dryers.
The results indicate that the legal standards fully
regulating the concentration of all microbial
groups, including pathogens, are necessary in order
to make the toilet users aware of the threat and to
determine the levels, above which corrective actions
will be required, such as: introducing more efficient
37
ventilation or replacement of equipment. Finally,
it can be concluded that using hand dryers does
not threaten human health.
Funding: The study was financed by the statutory measures of the Department of Microbiology, University of
Agriculture in Kraków. DS 3102/KM.
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16. Barker J., Jones M.V.: The potential spread of infection caused by aerosol contamination of surfaces after flushing
a domestic toilet. J Appl Microbiol 2005; 99(2): 339-347.
Address for correspondence:
Anna Lenart-Boroń
Department of Microbiology
University of Agriculture in Kraków
Mickiewicza ave 24/28
phone no.: 126624095
email: [email protected]

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